Move /src/test to /tests

tests/ui/codemap_tests/two_files.stderr

@@ -0,0 +1,15 @@
+error[E0404]: expected trait, found type alias `Bar`
+  --> $DIR/two_files.rs:5:6
+   |
+LL | impl Bar for Baz { }
+   |      ^^^ type aliases cannot be used as traits
+   |
+help: you might have meant to use `#![feature(trait_alias)]` instead of a `type` alias
+  --> $DIR/two_files_data.rs:5:1
+   |
+LL | trait Bar = dyn Foo;
+   |
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0404`.